Sahih Bukhari Volume 7, Book 72, Hadith Number 798.

Narrated By Hafsa : (The wife of the Prophet) I said, “O Allah’s Apostle! Why have the people finished their Ihram after performing the ‘Umra while you have not finished your lhram after your ‘Umra?” He said, “I have done Talbid (of my hair) and have decorated my Hadis with garlands, so I shall not finish my lhram till l have slaughtered my Hadi (animal for sacrifice).”